Multi-stage transmission for vehicle

ABSTRACT

A multi-stage transmission for a vehicle includes an input shaft, an output shaft, first to fourth planetary gear devices each having three rotary elements and transmitting rotary forces between the input and output shafts, and at least six shifting elements connected to the rotary elements of the planetary gear devices. Of the first planetary gear device, the first rotary element is installed to be fixable by any one of the shifting elements and permanently connected to the second rotary element of the third planetary gear device and the third rotary element of the fourth planetary gear device, the second rotary element is variably connected to the third rotary element of the second planetary gear device and the third rotary element of the third planetary gear device, and the third rotary element is variably connected to the first and second rotary elements of the second planetary gear device.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent ApplicationNumber 10-2015-0080474 filed Jun. 8, 2015, the entire contents of whichapplication are incorporated herein for all purposes by this reference

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention generally relates to a multi-stage transmissionfor a vehicle and, more particularly, to a multi-stage transmission ableto realize highest possible number of shifting stages using fewer partsand simple configuration, thereby improving fuel efficiency of avehicle.

Description of Related Art

Recent rising oil prices have driven worldwide car manufacturers intounlimited competition to improve fuel efficiency. In addition, greatefforts have been made to reduce the weight and improve the fuelefficiency of engines based on a variety of techniques such asdownsizing.

Meanwhile, among methods that can be sought for transmissions equippedin vehicles to improve fuel efficiency, there is a method allowing anengine to operate at more efficient operation points using themulti-staging of a transmission, thereby ultimately improving the fuelefficiency.

Further, such a multi-staging of a transmission allows an engine to beoperated in a relatively low RPM (revolutions per minute) range, therebyfurther improving the quietness of a vehicle.

However, as the number of shifting stages of a transmission increases,the number of internal parts constituting the transmission alsoincreases. This may lead to undesirable effects instead, such as thereduced mountability and transfer efficiency and the increased cost andweight of the transmission. Therefore, in order to maximize the effectof the improved fuel efficiency using the multi-staging of atransmission, it is important to devise a transmission structure able torealize maximum efficiency using a smalle number of parts and arelatively simple configuration.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the related art and/or other problems, andthe present invention is intended to provide a multi-stage transmissionfor a vehicle that is able to realize at least eleven forward shiftingstages and one reverse shifting stage with a relatively small number ofparts and a simple configuration such that an engine may be operated atoptimum operation points, thereby maximizing an improvement in the fuelefficiency of the vehicle, and the engine may be operated more quietly,thereby improving the quietness of the vehicle.

In order to achieve the above object and/or other objects, a multi-stagetransmission for a vehicle according to the present invention mayinclude: an input shaft; an output shaft; first, second, third andfourth planetary gear devices disposed between the input shaft and theoutput shaft to transmit rotary forces, each of the first to fourthplanetary gear devices having three rotary elements; and at least sixshifting elements connected to the rotary elements of the planetary geardevices. A first rotary element of the first planetary gear device maybe installed to be fixable by one shifting element of the at least sixshifting elements and permanently connected to a second rotary elementof the third planetary gear device and a third rotary element of thefourth planetary gear device, a second rotary element of the firstplanetary gear device may be variably connected to a third rotaryelement of the second planetary gear device and a third rotary elementof the third planetary gear device, and a third rotary element of thefirst planetary gear device may be variably connected to a first rotaryelement and a second rotary element of the second planetary gear device.The first rotary element of the second planetary gear device may beinstalled to be fixable by another shifting element of the at least sixshifting elements, the second rotary element of the second planetarygear device may be permanently connected to the input shaft, and thethird rotary element of the second planetary gear device may bepermanently connected to a first rotary element of the third planetarygear device. The first rotary element of the third planetary gear devicemay be permanently connected to a first rotary element of the fourthplanetary gear device. A second rotary element of the fourth planetarygear device may be permanently connected to the output shaft.

The first planetary gear device, the second planetary gear device, thethird planetary gear device and the fourth planetary gear device may besequentially arranged along an axial direction of the input shaft or theoutput shaft.

The first rotary element of the first planetary gear device may beinstalled to be fixable to a transmission case by means of a first brakeof the at least six shifting elements, the first rotary element of thesecond planetary gear device may be installed to be fixable to thetransmission case by means of a second brake of the at least sixshifting elements, and the other shifting elements of the at least sixshifting elements may be configured to constitute variable connectionstructures between the rotary elements of the planetary gear devices.

A first clutch of the at least six shifting elements may form a variableconnection structure between the third rotary element of the firstplanetary gear device and the first rotary element of the secondplanetary gear device; a second clutch of the at least six shiftingelements may form a variable connection structure between the thirdrotary element of the first planetary gear device and the second rotaryelement of the second planetary gear device; a third clutch of the atleast six shifting elements may form a variable connection structurebetween the second rotary element of the first planetary gear device andthe third rotary element of the second planetary gear device; and afourth clutch of the at least six shifting elements may form a variableconnection structure between the second rotary element of the firstplanetary gear device and the third rotary element of the thirdplanetary gear device.

In some aspects, a multi-stage transmission for a vehicle according tothe present invention may include: first, second, third and fourthplanetary gear devices each having three rotary elements, respectively;at least six shifting elements configured to variably provide frictionalforces; and first, second, third, fourth, fifth, sixth, seventh andeighth rotary shafts connected to the rotary elements of the first,second, third and fourth planetary gear devices, wherein the firstrotary shaft is an input shaft directly connected to a second rotaryelement of the second planetary gear device, the second rotary shaft isdirectly connected to a first rotary element of the first planetary geardevice, a second rotary element of the third planetary gear device and athird rotary element of the fourth planetary gear device, the thirdrotary shaft is directly connected to a second rotary element of thefirst planetary gear device, the fourth rotary shaft is directlyconnected to a third rotary element of the first planetary gear device,the fifth rotary shaft is directly connected to a first rotary elementof the second planetary gear device, the sixth rotary shaft is directlyconnected to a third rotary element of the second planetary gear device,a first rotary element of the third planetary gear device and a firstrotary element of the fourth planetary gear device, the seventh rotaryshaft is directly connected to a third rotary element of the thirdplanetary gear device, and the eighth rotary shaft is an output shaftdirectly connected to a second rotary element of the fourth planetarygear device; and wherein the at least six shifting elements includefirst, second, third and fourth clutches and first and second brakes,the first clutch is disposed between the fourth rotary shaft and thefifth rotary shaft, the second clutch is disposed between the firstrotary shaft and the fourth rotary shaft, the third clutch is disposedbetween the third rotary shaft and the sixth rotary shaft, the fourthclutch is disposed between the third rotary shaft and the seventh rotaryshaft, the first brake is disposed between the second rotary shaft and atransmission case, the second brake is disposed between the fifth rotaryshaft and the transmission case.

The first planetary gear device, the second planetary gear device, thethird planetary gear device and the fourth planetary gear device may besequentially arranged along an axial direction of the input shaft or theoutput shaft.

The first clutch of the at least six shifting elements may form avariable connection structure between the third rotary element of thefirst planetary gear device and the first rotary element of the secondplanetary gear device; the second clutch of the at least six shiftingelements may form a variable connection structure between the thirdrotary element of the first planetary gear device and the second rotaryelement of the second planetary gear device; the third clutch of the atleast six shifting elements may form a variable connection structurebetween the second rotary element of the first planetary gear device andthe third rotary element of the second planetary gear device; the fourthclutch of the at least six shifting elements may form a variableconnection structure between the second rotary element of the firstplanetary gear device and the third rotary element of the thirdplanetary gear device; the first brake of the at least six shiftingelements may form a variable connection structure between the firstrotary element of the first planetary gear device and the transmissioncase; and the second brake of the at least six shifting elements mayform a variable connection structure between the first rotary element ofthe second planetary gear device and the transmission case.

According to the present invention as set forth above, the multi-stagetransmission for a vehicle can realize at least eleven forward shiftingstages and one reverse shifting stage with a relatively small number ofparts and a simple configuration such that the engine may be operated atoptimum operation points, thereby maximizing an improvement in the fuelefficiency of the vehicle, and the engine may be operated more quietly,thereby improving the quietness of the vehicle.

The information disclosed in this Background section is only forenhancement of understanding of the general background of the inventionand should not be taken as an acknowledgement or any form of suggestionthat this information forms the prior art already known to a personskilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription when taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagram illustrating the configuration of a multi-stagetransmission for a vehicle according to an exemplary embodiment of thepresent invention;

FIG. 2 illustrates an operation mode table of the transmission shown inFIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims. Wherever possible,the same reference numerals will be used throughout the drawings and thedescription to refer to the same or like parts.

Referring to FIG. 1, a multi-stage transmission for a vehicle accordingto an exemplary embodiment of the present invention may include an inputshaft IN; an output shaft OUT; first to fourth planetary gear devicesPG1, PG2, PG3 and PG4 disposed between the input shaft IN and the outputshaft OUT to transmit rotary forces, each of the first to fourthplanetary gear devices PG1 to PG4 having three rotary elements; and atleast six shifting elements connected to rotary elements of the first tofourth planetary gear devices PG1 to PG4.

A first rotary element S1 of the first planetary gear device PG1installed to be fixable by one shifting element of the at least sixshifting elements and permanently connected to a second rotary elementC3 of the third planetary gear device PG3 and a third rotary element R4of the fourth planetary gear device PG4. A second rotary element C1 ofthe first planetary gear device PG1 may be variably connected to a thirdrotary element R2 of the second planetary gear device PG2 and a thirdrotary element R3 of the third planetary gear device PG3. A third rotaryelement R1 of the first planetary gear device PG1 may be variablyconnected to a first rotary element S2 and a second C2 of the secondplanetary gear device PG2.

The first rotary element S2 of the second planetary gear device PG2 maybe installed to be fixable by another shifting element of the at leastsix shifting elements, the second rotary element C2 of the secondplanetary gear device PG2 may be permanently connected to the inputshaft IN, and the third rotary element R2 of the second planetary geardevice PG2 may be variably connected to the first rotary element S3 ofthe third planetary gear device PG3.

The first rotary element S3 of the third planetary gear device PG3 maybe permanently connected to a first rotary element S4 of the fourthplanetary gear device PG4. A second rotary element C4 of the fourthplanetary gear device PG4 may be permanently connected to the outputshaft OUT.

In the present exemplary embodiment, the first planetary gear devicePG1, the second planetary gear device PG2, the third planetary geardevice PG3 and the fourth planetary gear device PG4 may be sequentiallyarranged along the axial direction of the input shaft IN and/or theoutput shaft OUT.

The first rotary element S1 of the first planetary gear device PG1 maybe installed to be fixable to the transmission case CS by means of afirst brake B1 of the at least six shifting elements. The first rotaryelement S2 of the second planetary gear device PG2 may be installed tobe fixable to the transmission case CS by means of a second brake B2 ofthe at least six shifting elements.

The other shifting elements of the at least six shifting elements may beconfigured to constitute variable connection structures between therotary elements of the planetary gear devices.

For example, a first clutch CL1 of the at least six shifting elementsmay form a variable connection structure between the third rotaryelement R1 of the first planetary gear device PG1 and the first rotaryelement S2 of the second planetary gear device PG2. A second clutch CL2of the at least six shifting elements may form a variable connectionstructure between the third rotary element R1 of the first planetarygear device PG1 and the second rotary element C2 of the second planetarygear device PG2. A third clutch CL3 of the at least six shiftingelements may form a variable connection structure between the secondrotary element C1 of the first planetary gear device PG1 and the thirdrotary element R2 of the second planetary gear device PG2. A fourthclutch CL4 of the at least six shifting elements may form a variableconnection structure between the second rotary element C1 of the firstplanetary gear device PG1 and the third rotary element R3 of the thirdplanetary gear device PG3.

In the present exemplary embodiment, the first rotary element S1, thesecond rotary element C1 and the third rotary element R1 of the firstplanetary gear device PG1 are a first sun gear, a first carrier and afirst ring gear, respectively. The first rotary element S2, the secondrotary element C2 and the third rotary element R2 of the secondplanetary gear device PG2 are a second sun gear, a second carrier and asecond ring gear, respectively. The first rotary element S3, the secondrotary element C3 and the third rotary element R3 of the third planetarygear device PG3 are a third sun gear, a third carrier and a third ringgear, respectively. The first rotary element S4, the second rotaryelement C4 and the third rotary element R4 of the fourth planetary geardevice PG4 are a fourth sun gear, a fourth carrier and a fourth ringgear, respectively.

The multi-stage transmission for a vehicle configured as above may alsobe presented as follows.

Specifically, the multi-stage transmission for a vehicle according tothe present invention may include the first to fourth planetary geardevices PG1 to PG4 each having the three rotary elements; the sixshifting elements configured to variably provide frictional force; andeight rotary shafts connected to the rotary elements of the first tofourth planetary gear devices PG1 to PG4.

Hence, of the eight rotary shafts, the first rotary shaft RS1 may be theinput shaft IN directly connected to the second rotary element C2 of thesecond planetary gear device PG2. The second rotary shaft RS2 may bedirectly connected to the first rotary element S1 of the first planetarygear device PG1, the second rotary element C3 of the third planetarygear device PG3 and the third rotary element R4 of the fourth planetarygear device PG4. The third rotary shaft RS3 may be directly connected tothe second rotary element C1 of the first planetary gear device PG1. Thefourth rotary shaft RS4 may be directly connected to the third rotaryelement R1 of the first planetary gear device PG2. The fifth rotaryshaft RS5 may be directly connected to the first rotary element S2 ofthe second planetary gear device PG2. The sixth rotary shaft RS6 may bedirectly connected to the third rotary element R2 of the secondplanetary gear device PG2, the first rotary element S3 of the thirdplanetary gear device PG3 and the first rotary element S4 of the fourthplanetary gear device PG4. The seventh rotary shaft RS7 may be directlyconnected to the third rotary element R3 of the third planetary geardevice PG3. The eighth rotary shaft RS8 may be the output shaft OUTdirectly connected to the second rotary element C4 of the fourthplanetary gear device PG4.

In addition, of the six shifting elements, the first clutch CL1 may bedisposed between the fourth rotary shaft RS4 and the fifth rotary shaftRS5. The second clutch CL2 may be disposed between the first rotaryshaft RS1 and the fourth rotary shaft RS4. The third clutch CL3 may bedisposed between the third rotary shaft RS3 and the sixth rotary shaftRS6. The fourth clutch CL4 may be disposed between the third rotaryshaft RS3 and the seventh rotary shaft RS7. The first brake B1 may bedisposed between the second rotary shaft RS2 and the transmission caseCS. The second brake B2 may be disposed between the fifth rotary shaftRS5 and the transmission case CS.

The first planetary gear device PG1, the second planetary gear devicePG2, the third planetary gear device PG3 and the fourth planetary geardevice PG4 may be sequentially arranged along the axial direction of theinput shaft IN and/or the output shaft OUT.

A first clutch CL1 of the at least six shifting elements may form avariable connection structure between the third rotary element R1 of thefirst planetary gear device PG1 and the first rotary element S3 of thethird planetary gear device PG3. A second clutch CL2 of the at least sixshifting elements may form a variable connection structure between thethird rotary element R1 of the first planetary gear device PG1 and thesecond rotary element C2 of the second planetary gear device PG2. Athird clutch CL3 of the at least six shifting elements may form avariable connection structure between the second rotary element C1 ofthe first planetary gear device PG1 and the third rotary element R2 ofthe second planetary gear device PG2. A fourth clutch CL4 of the atleast six shifting elements may form a variable connection structurebetween the second rotary element C1 of the first planetary gear devicePG1 and the third rotary element R3 of the third planetary gear devicePG3. The first brake B1 may form a variable connection structure betweenthe first rotary element S1 of the first planetary gear device PG1 andthe transmission case CS. The second brake B2 may form a variableconnection structure between the first rotary element S2 of the secondplanetary gear device PG2 and the transmission case CS.

As set forth above, the multi-stage transmission for a vehicle accordingto the present invention including the four simple planetary geardevices and the six shifting elements realizes eleven forward shiftingstages and one reverse shifting stage according to the operation modetable as illustrated in FIG. 2. Since the multi-stage shifting stages often shifting stages can be embodied based on a relatively small numberof parts and a simple configuration, the multi-stage transmission for avehicle can contribute to the improved fuel efficiency and quietness ofa vehicle, thereby ultimately improving the marketability of thevehicle.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A multi-stage transmission for a vehicle,comprising: an input shaft; an output shaft; first, second, third andfourth planetary gear devices disposed between the input shaft and theoutput shaft to transmit rotary forces, each of the first, second, thirdand fourth planetary gear devices having three rotary elements; and atleast six shifting elements connected to the rotary elements of theplanetary gear devices; wherein a first rotary element of the firstplanetary gear device is installed to be fixable by one shifting elementof the at least six shifting elements and permanently connected to asecond rotary element of the third planetary gear device and a thirdrotary element of the fourth planetary gear device, a second rotaryelement of the first planetary gear device is variably connected to athird rotary element of the second planetary gear device and a thirdrotary element of the third planetary gear device, and a third rotaryelement of the first planetary gear device is variably connected to afirst rotary element and a second rotary element of the second planetarygear device; wherein the first rotary element of the second planetarygear device is installed to be fixable by another shifting element ofthe at least six shifting elements, the second rotary element of thesecond planetary gear device is permanently connected to the inputshaft, and the third rotary element of the second planetary gear deviceis permanently connected to a first rotary element of the thirdplanetary gear device; wherein the first rotary element of the thirdplanetary gear device is permanently connected to a first rotary elementof the fourth planetary gear device; and wherein a second rotary elementof the fourth planetary gear device is permanently connected to theoutput shaft.
 2. The multi-stage transmission according to claim 1,wherein the first planetary gear device, the second planetary geardevice, the third planetary gear device and the fourth planetary geardevice are sequentially arranged along an axial direction of the inputshaft or the output shaft.
 3. The multi-stage transmission according toclaim 2, wherein: the first rotary element of the first planetary geardevice is installed to be fixable to a transmission case by means of afirst brake of the at least six shifting elements; the first rotaryelement of the second planetary gear device is installed to be fixableto the transmission case by means of a second brake of the at least sixshifting elements; and the other shifting elements of the at least sixshifting elements are configured to constitute variable connectionstructures between the rotary elements of the planetary gear devices. 4.The multi-stage transmission according to claim 3, wherein: a firstclutch of the at least six shifting elements forms a variable connectionstructure between the third rotary element of the first planetary geardevice and the first rotary element of the second planetary gear device;a second clutch of the at least six shifting elements forms a variableconnection structure between the third rotary element of the firstplanetary gear device and the second rotary element of the secondplanetary gear device; a third clutch of the at least six shiftingelements forms a variable connection structure between the second rotaryelement of the first planetary gear device and the third rotary elementof the second planetary gear device; and a fourth clutch of the at leastsix shifting elements forms a variable connection structure between thesecond rotary element of the first planetary gear device and the thirdrotary element of the third planetary gear device.
 5. A multi-stagetransmission for a vehicle, comprising: first, second, third and fourthplanetary gear devices each having three rotary elements, respectively;at least six shifting elements configured to variably provide frictionalforces; and first, second, third, fourth, fifth, sixth, seventh andeighth rotary shafts connected to the rotary elements of the first,second, third and fourth planetary gear devices; wherein the firstrotary shaft is an input shaft directly connected to a second rotaryelement of the second planetary gear device, the second rotary shaft isdirectly connected to a first rotary element of the first planetary geardevice, a second rotary element of the third planetary gear device and athird rotary element of the fourth planetary gear device, the thirdrotary shaft is directly connected to a second rotary element of thefirst planetary gear device, the fourth rotary shaft is directlyconnected to a third rotary element of the first planetary gear device,the fifth rotary shaft is directly connected to a first rotary elementof the second planetary gear device, the sixth rotary shaft is directlyconnected to a third rotary element of the second planetary gear device,a first rotary element of the third planetary gear device and a firstrotary element of the fourth planetary gear device, the seventh rotaryshaft is directly connected to a third rotary element of the thirdplanetary gear device, and the eighth rotary shaft is an output shaftdirectly connected to a second rotary element of the fourth planetarygear device; and wherein the at least six shifting elements includefirst, second, third and fourth clutches and first and second brakes,the first clutch is disposed between the fourth rotary shaft and thefifth rotary shaft, the second clutch is disposed between the firstrotary shaft and the fourth rotary shaft, the third clutch is disposedbetween the third rotary shaft and the sixth rotary shaft, the fourthclutch is disposed between the third rotary shaft and the seventh rotaryshaft, the first brake is disposed between the second rotary shaft and atransmission case, the second brake is disposed between the fifth rotaryshaft and the transmission case.
 6. The multi-stage transmissionaccording to claim 5, wherein the first planetary gear device, thesecond planetary gear device, the third planetary gear device and thefourth planetary gear device are sequentially arranged along an axialdirection of the input shaft or the output shaft.
 7. The multi-stagetransmission according to claim 5, wherein: the first clutch of the atleast six shifting elements forms a variable connection structurebetween the third rotary element of the first planetary gear device andthe first rotary element of the second planetary gear device; the secondclutch of the at least six shifting elements forms a variable connectionstructure between the third rotary element of the first planetary geardevice and the second rotary element of the second planetary geardevice; the third clutch of the at least six shifting elements forms avariable connection structure between the second rotary element of thefirst planetary gear device and the third rotary element of the secondplanetary gear device; the fourth clutch of the at least six shiftingelements forms a variable connection structure between the second rotaryelement of the first planetary gear device and the third rotary elementof the third planetary gear device; the first brake of the at least sixshifting elements forms a variable connection structure between thefirst rotary element of the first planetary gear device and thetransmission case; and the second brake of the at least six shiftingelements forms a variable connection structure between the first rotaryelement of the second planetary gear device and the transmission case.